This invention relates to a vacuum regulator, such as the type used to regulate vacuum pressure of a medical regulating vacuum controller to control the applicaiton of vacuum pressure for drawing bodily fluids from a patient, and more particularly, to such a vacuum regulator having a valve stem carried by a movable wall of a regulation chamber.
In various medical applications vacuum pressure controllers are employed to control the level of vacuum pressure applied to draw bodily fluids from a patient. Such controllers have a housing within which is contained a vacuum pressure meter, an inlet port for connection with a supply of vacuum pressure, a nonregulated or line vacuum chamber in open communication with the inlet port, a regulation vacuum chamber with a valve opening for controlled communication with the line vacuum chamber and with an outlet port for connection of regulated vacuum pressure to the patient.
The vacuum regulation chamber includes a well within which is slideably received a vacuum regulating cartridge. The cartridge carries a movably mounted valve head at the end of a valve stem for mating engagement with a valve seat of the valve opening in the well. The carriage body is mounted for sliding receipt of a projecting valve guide portion thereof within the well in response to relative rotation of a knob to selectively move the valve head to different positions relative to the valve seat. These different positions correspond to different vacuum levels selected from a range of different vacuum pressures.
In known cartridges, the cartridge body contains therewithin a moving wall of the regulation chamber in the form of a bellows-like apparatus or other flexible diaphragm to which one end of the valve stem is attached. The moving wall responds to decreases in pressure in the well to move the valve head closer to the valve opening to decrease the effective valve opening and thereby increase the pressure in the well. Likewise, when the vacuum decreases in the well, the bellows respond by moving the valve head away from the valve seat to increase the vacuum. In this way the vacuum which appears at the outlet port and provided to the patient is regulated relative to the line vacuum.
The valve stem extends from the one end attached to the movable wall within the cartridge body through the valve stem portion of the cartridge body within the well to the valve head outside the cartridge body but within the well. Specifically, the valve stem extends through an elongate passageway through the valve stem guide portion.
A problem which has been encountered with this arrangement is that binding can occur between the valve stem and the elongate guide passageway through which it extends. When such binding occurs, it causes an erratic relationship between the adjustment of the knob and the resultant outlet vacuum level achieved thereby. This, in turn, causes accurate adjustment of the vacuum level to be both difficult to achieve and unreliable.